Human LH and FSH will be dissociated into their alpha and beta subunits and the individual subunits will be purified and their primary amino acid sequence determined. The physical properties of the isolated subunits will be studied and compared with the native hormone. Association and dissociations constants will be determined. Antibodies will be prepared to tryptic peptides of the citroconylated subunits and used to localize the active site of the hormone. The LH receptor in rat ovarian tissue will be isolated and characterized.